Method of producing clad wire

ABSTRACT

Aluminum rod of indefinite length is wrapped with a copper sheathing having a longitudinal lock seam and is then passed through hydrostatic extrusion apparatus. The heat and pressure of the extrusion process bond the copper to the aluminum and weld the lock seam as the copper-sheathed aluminum rod is extruded to produce copper clad aluminum wire of indefinite length. Materials other than copper and aluminum may be employed in the practice of the present invention.

United States Patent 1 Fuchs, Jr.

[ Dec. 11, 1973 METHOD 0F PRODUCING CLAD WIRE [75 Inventor: Francis Joseph Fuchs, Jr., Princeton Junction, NJ.

[73] Assignee: Western Electric Company,

Incorporated, New York, NY.

[22] Filed: Aug. 4, 1972 [21] Appl. No.: 277,892

[52] US. Cl 29/470.6, 29/473.7, 29/474.1, 29/479 [51] Int. Cl 823k 31/02 [58] Field of Search 29/470.l, 475, 479, 29/473.3, 473.7, 473.9, 474.1, 470.6

[56] References Cited UNITED STATES PATENTS 910,814 1/1909 Hellmich 29/474.l X 1,571,412 2/1926 lrvin 29/470.1 3,282,660 11/1966 Pendleton... 29/473.3 X 3,434,320 3/1969 Green 72/60 3,509,617 5/1970 Winter 29/479 X 3,604,102 9/1971 Boccalari et al.. 29/479 X 3,631,586 l/1972 Bearpark et al. 29/475 X 3,646,796 3/1972 Tanaka et a1. 72/258 3,654,687 4/1972 Burstrom 72/60 Primary ExaminerRichard B. Lazarus Attorney-W. M. Kain et a1.

[57] ABSTRACT Aluminum rod of indefinite length is wrapped with a copper sheathing having a longitudinal lock seam and is then passed through hydrostatic extrusion apparatus. The heat and pressure of the extrusion process bond the copper to the aluminum and weld the lock seam as the copper-sheathed aluminum rod is extruded to produce copper clad aluminum wire of indefinite length. Materials other than copper and aluminum may be employed in the practice of the present invention.

7 Claims, 3 Drawing Figures 1 METHOD OF PRODUCING CLAD WIRE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, broadly speaking, to a method for producing clad wire. More specifically, this invention relates to a method wherein a metallic (e.g., aluminum) rod is continuously clad with a metallic (e.g., copper) sheathing, and the clad rod is then continuously extruded to produce clad wire.

2. Description of the Prior Art I A metallic wire consisting of a core of one metal and a cladding of another metal often provides certain advantages over a solid wire of one metal. Thus, copperclad aluminum wire has been recognized as having more desirable properties than are offered by solid copper wire and solid aluminum wire. In comparison to solid copper wire, copper-clad aluminum wire has a lower specific weight and is much less expensive inasmuch as aluminum is cheaper than copper on a weight basis. In comparison to solid aluminum wire, copper: clad aluminum wire is a better conductor of electricity.

Various methods have been proposed by means of which copper-clad aluminum wire may be produced.

,U. S. Pat. No. 3,631,586 (1972) to Bearpark et al. discloses a non-continuous method wherein a discrete billet of aluminum is inserted into a copper tube and the discrete composite tube is then totally inserted into the chamber of an extrusion apparatus, whence a finite length of copper-clad aluminum wire is extruded.

U. S. Pat. No. 3,646,796 (1972) to Tanaka et al. discloses a method wherein heated core wire is passed through a die and simultaneously a discrete billet of cladding material, totally enclosed in a chamber upstream of the die, is extruded through the die around the core wire.

U. S. Pat. No. 3,654,687 (1972 to Burstrom et al. discloses a method forhydrostatically extruding a discrete billet of core material in a discrete casing of surface material to form a finite length of cased elongated product. I Y

The foregoing patents disclose non-continuous operations which simply are not suited to large scale commercial requirements for copper-clad aluminum wire.

Continuousprocesses' for making copper-clad alumi-' num wire are known; However, these processes have certain shortcomings.

U. S. Pat. No. 3,408,727 (1968) to Dion discloses a method for continuously cladding with copper an aluminum wire core of indefinite length. Opposed rotating rolls, each provided with a semicircular groove, the said grooves facing each other, draw the aluminum wire core and two flat copper strips surrounding the aluminum wire core through the grooves whereupon each copper strip is curved around half the surface of the aluminum wire core and is bonded in the solid phase thereto. The copper strips meet along the two sides of the aluminum wire core and produce longitudinal flashings of copper which are unacceptable in the finished product and which therefore must be removed in a subsequent finishing operation.

U. S. Pat. No. 3,648,356 (1972) to Ziemek discloses a method for continuously cladding aluminum rod with copper. Copper tape from r a roll is continuously wrapped around the aluminum rod and the meeting longitudinal edges of the copper wrapping are welded in a protective gas atmosphere before the copper-clad aluminum rod is passed through a die to produce copper-clad aluminum wire. The need for welding adds to the expense of the operation.

SUMMARY OF THE INVENTION One of the objects of this invention is to provide an improved method for producing clad wire.

Another of the objects of this invention is to provide an improved method for continuously sheathing a metallic (e.g., aluminum) rod ofindefinite length with another metallic (e.g., copper) covering and continuously extruding the sheathed rod to produce clad wire of indefinite length. 1

Other and further objects of this invention will become apparent during the course of the following specification and by reference to the accompanying drawing and the appended claims.

Briefly, I have discovered that the foregoing objects may be attained by continuously applying a metallic (e.g., copper) sheathing to a metallic (e.g., aluminum) rod, the sheathing having formed therein a lock seam running longitudinally of the rod and having an overall thickness equal to the thickness of the sheathing, the sheathed rod being continuously extruded to reduce the transverse cross-section thereof to the cross-section of the desired clad rod, the heat and pressure of the extrusion operation bonding the two metals together and welding the lock seam.

BRIEF DESCRIPTION OF THE DRAWING Referring now to the drawing in which like numerals represent like parts in the several views:

FIG. 1 represents a view, partially diagrammatic, showing a metallic (e.g., aluminum rod of indefinite length being sheathed by a metallic (e.g., copper) tape or strip of indefinite length and extruded to produce clad wire (e.g., copper-clad aluminum wire) of indefinite length.

FIG. 2 represents an enlarged partial transverse cross-section of the rod and sheathing, showing the lock seam.

FIG. 3 represents an enlarged transverse cross- I section of the clad wire.'

.DES CRIPTION OF THE PREFERRE EMBODIMENT Metallic (e.g., aluminum) rod 1 of indefinite length is advanced past wire brush cleaner 2 indicated diagrammatically and in phantom in FIG. 1, whereby to remove oxide and the like from the surface of the said rod 1.

Simultaneously, flat metallic (e.g., copper) strip 3 of indefinite length is advanced past wire brush cleaner 4 indicated diagrammatically and in phantom in FIG. 1. Advantageously, the metallic strip 3 may be continuously produced by rolling a metallic rod (not shown) of indefinite length.

The cleaned metallic rod 1 and metallic strip 3 enter forming rolls 5, indicated diagrammatically and in phantom in FIG. 1. Forming rolls 5 are of a design and construction which is well known to those familiar with the art, and no detailed description thereof is deemed necessary to a full and complete understanding of the present invention. Forming rolls 5 continuously wrap the metallic strip 3 around the metallic rod 1 as a sheathing 6 with longitudinal lock seam 7 as indicated in FIG. 2. Those ends of the metallic strip 3 which form the lock seam 7 of sheathing 6 have been sufficiently reduced in thickness by the forming rolls 5 so that the overall thickness of the lock seam 7 is equal to the thickness of the metallic sheathing 6.

Metallic rod 1 with metallic sheathing 6 passes continuously from forming rolls 5 to extruder 8 indicated diagrammatically in FIG. 1. Advantageously, extruder 8 may be continuous hydrostatic extrusion apparatus of the type described in U. S. Pat. No. 3,667,267. Lock seam 7 functions as a seal to prevent the infiltration of extrusion fluid between rod 1 and sheathing 6 in the extruder 8. The metals are bonded to each other and lock seam 7 is welded under the heat and pressure generated in extruder 8 as the sheathed rod 1 passes through the die 9 to produce a composite wire 10 of indefinite length and having a metallic core '1 1 anda substantially' seamless metallic cladding l2 thereon. Advantageously, a sizing die- 13 may be interposed between forming rolls 5 and extruder 8 to insure that sheathing 6 fits snugly on rod 1.

By way of example, metallic rod 1 may be an aluminum rod 0.320 inch in diameter, and metallic strip 3 may be a copper strip 0.020 inch thick. This would provide a copper cladding 12 of 0.001 inch thickness of 24 gauge wire.

It will, of course, be understood that the pressure and temperature experienced by metallic rod 1 and sheathing 6 as they pass through extruder 8 should be at least equal to the temperature and pressure required to bond the two metals together as well as to effect a welding of lock seam 7. Generally, hydrostatic extrusion apparatus particularly of the type shown in U. S.'Pat. No. 3,667,267 operates under pressures well above that required for bonding and welding and, in most operations, the degree of reduction of rod 1 to wire 3 will generate temperatures well above that required for bonding and welding.

Thus, in extruding it; inches diameter aluminum rod of electrical conductivity grade to produce 14 gauge wire, the die stem stress (assuming the die stem has the same diameter as the rod) must be approximately 76,000 psi and the extrusion fluid pressure, as is commonly known to those familiar with-the art, will always be greater than this; moreover, the extrusion operation will raise the metal temperature to approximately 300 F above ambient. The extrusion fluid pressure and the metal temperature in the foregoing example are well above the minimum pressure and temperature required to bond copper to aluminum and to weld a lock seam in 0.020 inch copper strip.

While this specification specifically mentions copper and aluminum, it will be understood that the invention is not to be limited to these materials, and that other materials may be employed in the practice of the present invention. 1

I claim:

1. Method for producing a clad product, said method comprising: I I

a. forming a sheathing of first material having two interlocked-edges providing a fluid-tight lock seam therein around and in contact with a member of second material;

b. reducing the cross-section of said member and said sheathing by applying pressurized fluid to the surface of said sheathing including said lock seam,

said reduction generating heat, the combination of said heat and the pressure of said fluid welding said lock seam;

0. whereby to produce a substantially seamless clad product.

2. Method as in claim 1, wherein the overall thickness of said lock seam prior to reducing the crosssection thereof is equal to the thickness of said sheathing prior to reducing the cross-section thereof, whereby the cladding on the product has substantially uniform thickness throughout.

3. Method as in claim 1, wherein step (b) the first and second materials are bonded to each other.

4. Method for continuously producing a clad elongated product of indefinite length, said method comprising:

a. continuously advancing an elongated member of first metallic material and of indefinite length past a station;

b. continuously advancing a strip of second metallic material of indefinite length toward engagement with said elongated member at said station;

c. continuously forming at said station around and in contact with said elongated member said strip as a sheathing having interlocked edges providing a fluid-tight lock seam extending longitudinally of the elongated member;

d. downstream of said station, continuously hydrostatically extruding said elongated member and said sheathing through an extrusion die by applying pressurized fluid to the longitudinal surface of said sheathing including said lock seam thereby to continuously reduce the transverse cross-section of said elongated member and said sheathing, said hydrostatic extrusion generating heat, the combination of said heat and the pressure of said fluid welding said lock seam;

e. thereby to continuously produce substantially seamless clad elongated product of indefinite length.

5. Method as in claim 4, wherein the overall thickness of said lock seam prior to extrusion is equal to the thickness of said sheathing prior to extrusion, whereby the cladding on the product has substantially uniform thickness throughout.

6. Method as in claim 4, wherein step (d) the first and second metallic materials are bonded to each other.

7. Method for continuously producing copper-clad aluminum wire of indefinite length, said method comprising:

a. continuously advancing aluminum rod of indefinite length past a station;

b. continuously advancing copper strip of indefinite length toward engagement with said aluminum rod at said station;

c. continuously forming at said station around and in contact with said aluminum rod said copper strip as a sheathing having interlocked edges providing a fluid-tight lock seam extending longitudinally of said rod, the overall thickness of said lock seam equalling the thickness of said sheathing;

d. downstream of said station, continuously hydrostatically extruding said aluminum rod and copper sheathing through an extrusion die by applying pressurized fluid to the longitudinal surface of said sheathing including said lock seam to reduce the transverse cross-section of said aluminum rod and copper sheathing, said hydrostatic extrusion gener- 3,777,361 6 ating heat, the combination of said heat and the clad aluminum wire ofindefinite length, the copper pressure of said fluid welding said lock seam and cladding having substantially uniform thickness bonding the copper to the aluminum; throughout. e. whereby to produce substantially seamless copper UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION p No. 3,777,3 1 Dated December 11 1973 lnvemofls) FRANCIS JOSEPH FUCHS, JR.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Add to those references listed under References Cited in the Title page the following references cited in Notice of References dated August 10, 1973: L69,662 2/1892 Greenfield .29/505; 2,210,338 8/1990 Quarnstrom...333/7 L; 3,096, 577 7/1963 Carlson et a1...29/ L73.3; 3,328,87 L 7/1967 Davis et a1...29/A70.5; 3,399,557 9/1968 Lang et al...72/258; 3,702,A97 11/1972 Dion et al...29/ L7 L.3; 3,71%701 2/1973 Dion et al .29/A7 Ll; 668,298 8/1963 Canada; 686,659 5/196 r Canada; Transactions of the ASME, March 1972, pages 7880.-

Column 2, line 3 1, (e.g., aluminum should read --(e.g., aluminum)-.

Column '3, line 21, "of 24" should read --on 2 L--.

Column L, line 20, material of" should read ---material and of--.

Signed and sealed this 23rd day of July 197A.

(SEAL) ATTEST I MCCOY Mo GIBSON, JR. 0. MARSHALL DANN I Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION December 11 1973 Patent No. 3)??? 361 Dated FRANCIS JOSEPH FUCHS, JR.

lnventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Add to those references listed under References Cited in the Title page the following references cited in Notice of References dated August 10, 1973: +69,662 2/1892 Greenfield .29/505; 2,210,338 8/1990 Quarnstromm333/7 L; 3,096,577 7/1963 Carlson et al...29/ L73.3; 3,328,874 7/1967 Davis et a1...29/. +7o.5;; 3,399,557 9/1968 Lang et a1..'.72/258; 3,702,997 11/1972 Dion et a1...29/ L7 L.3; 3,71%701 2/1973 Dion et a1 .29/ V/ L1; 668,298 8/1963 Canada; 686,659 5/1969 Canada; Transactions of the ASME, March 1972, pages 78-80.--

Column 2, line 34, "(e.g., aluminum should read -(e.g., aluminum)--.

Column '3, line" 2%, of 2 1" should read---on 2 l--.

Column L, line 20, material of should read --material and of--.

Signed and sealed this 23rd day of July 1971.

(SEAL) ATTEST MCCOY M, GIBSON,'JR C. vMARSHALL DANN Attesting Officer Commissioner of Patents 

2. Method as in claim 1, wherein the overall thickness of said lock seam prior to reducing the cross-section thereof is equal to the thickness of said sheathing prior to reducing the cross-section thereof, whereby the cladding on the product has substantially uniform thickness throughout.
 3. Method as in claim 1, wherein step (b) the first and second materials are bonded to each other.
 4. Method for continuously producing a clad elongated product of indefinite length, said method comprising: a. continuously advancing an elongated member of first metallic material and of indefinite length past a station; b. continuously advancing a strip of second metallic material of indefinite length toward engagement with said elongated member at said station; c. continuously forming at said station around and in contact with said elongated member said strip as a sheathing having interlocked edges providiNg a fluid-tight lock seam extending longitudinally of the elongated member; d. downstream of said station, continuously hydrostatically extruding said elongated member and said sheathing through an extrusion die by applying pressurized fluid to the longitudinal surface of said sheathing including said lock seam thereby to continuously reduce the transverse cross-section of said elongated member and said sheathing, said hydrostatic extrusion generating heat, the combination of said heat and the pressure of said fluid welding said lock seam; e. thereby to continuously produce substantially seamless clad elongated product of indefinite length.
 5. Method as in claim 4, wherein the overall thickness of said lock seam prior to extrusion is equal to the thickness of said sheathing prior to extrusion, whereby the cladding on the product has substantially uniform thickness throughout.
 6. Method as in claim 4, wherein step (d) the first and second metallic materials are bonded to each other.
 7. Method for continuously producing copper-clad aluminum wire of indefinite length, said method comprising: a. continuously advancing aluminum rod of indefinite length past a station; b. continuously advancing copper strip of indefinite length toward engagement with said aluminum rod at said station; c. continuously forming at said station around and in contact with said aluminum rod said copper strip as a sheathing having interlocked edges providing a fluid-tight lock seam extending longitudinally of said rod, the overall thickness of said lock seam equalling the thickness of said sheathing; d. downstream of said station, continuously hydrostatically extruding said aluminum rod and copper sheathing through an extrusion die by applying pressurized fluid to the longitudinal surface of said sheathing including said lock seam to reduce the transverse cross-section of said aluminum rod and copper sheathing, said hydrostatic extrusion generating heat, the combination of said heat and the pressure of said fluid welding said lock seam and bonding the copper to the aluminum; e. whereby to produce substantially seamless copper clad aluminum wire of indefinite length, the copper cladding having substantially uniform thickness throughout. 